This thesis examines the operation and control of a radiofrequency ion source.

This thesis examines temperature dependence of magnetic susceptibility of the organic free radical galvinoxyl.

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Traditionally civil infrastructure designs were rendered using rainfall data from dated historical records. However, recent studies have shown that the magnitude and intensity of historical precipitation events do not exhibit the extreme nature of precipitation events that are projected to occur in the future. Increasing extreme rainfall trends have already been documented in Canada. Therefore there are growing concerns that the aging infrastructure in southern Ontario will be unable to function effectively and as a result the frequency of floods is expected to increase. Updating intensity-duration-frequency (IDF) curves to account for extreme precipitation events is vital to ensure that the consequences of floods are mitigated. This study first reviewed the most robust techniques for updating IDF curves, and applied a select set of approaches to create IDF curves for stations within southern Ontario. Three robust techniques – the at-site method, the regional frequency analysis method, and a future IDF curve development technique – were compared with one another to determine which technique was most suitable for updating IDF curves in southern Ontario. Results showed that the difference between the at-site method and the regional frequency analysis method was marginal for short return periods, however for larger return periods larger differences were observed. Future IDF statistic results showed that for the 2050s there were minor differences in the increases in rainfall intensities when comparing with the at-site and the regional frequency analysis method. For the 2100s there were larger increases in rainfall intensities compared to the at-site and the regional frequency analysis method, especially for larger return periods. These results suggest that it is worthwhile for regions within southern Ontario to update their IDF curves using the future IDF curve technique, however it is recommended that additional climate models, emission scenarios and downscaling techniques involved in future IDF curve construction are explored. / Thesis / Master of Science (MSc)

A study of nocturnal inversions in the Central Plains of the United States was conducted using 15 National Weather Service stations. Radiosonde data from 1960 to 2007 were analyzed in order to assess any regional trends in inversion characteristics. Previous research suggests that the urban heat effect counteracts the inversion effect and, therefore, a change in inversion characteristics was expected. Yearly, seasonal, and monthly statistical analyses revealed few trends in inversion frequency, intensity, and depth. Using statistical and graphical analyses, no overarching changes in nocturnal inversions were observable over the Central Plains during this time. While not explicitly the intention of this study, one consistent result was displayed through the average soundings: an overall atmospheric warming (from near surface to 500 mb) existed at thirteen of the fifteen sites.

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